In LTE (Long Term Evolution), as shown in FIG. 9, radio base stations eNB#A and eNB#B are configured to allocate C-RNTIs (Cell-Radio Network Temporary Identities) to mobile stations UE performing communication in cells #A and #B under the radio base stations eNB#A and eNB#B and to perform data exchange with the mobile stations UE (see Non-Patent Document 1).
The allocation of C-RNTIs is performed cell by cell. In LTE, as shown in FIG. 9, the same C-RNTI cannot be allocated to a mobile station UE#1 and a mobile station UE#2 which perform communication in the same cell #A. Meanwhile, the same C-RNTI can be allocated to the mobile station UE#1 (or the mobile station UE#2) and a mobile station UE#3 which perform communication in the different cells #A and #B, respectively.
The C-RNTIs are configured to be allocated in a “Contention based RA (Random Access) procedure” and a handover procedure.
Moreover, the radio base station eNB is configured to allocate resources for downlink data transmission and uplink data transmission by using the C-RNTI allocated to each of the mobile stations UE.
Meanwhile, in the “Rel-12 workshop” of 3GPP, many proposals on “Small cell enhancement” have been made as a topic of FRA (Future Radio Access).
In such proposals, a concept related to “phantom cell” is being considered.
As shown in FIG. 10, unlike a conventional macro cell, the phantom cell forms one large cell by combining many small cells and can cover a large area.